Lantern.



L. W. NCOLS.

LANTERN.

APPUCTON FILED APR. 5| 19|]- .l ,298,084. Patented Mar. 25,1919.

` 3 SHEETS-SHEET L. W. NICOLS.

LANTERN.

APPLICATION FILED APR. 5 1911.

Patented Mar. 25, 1919.

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atn-uy@ WITNESSES L. W. NICOLS.

LANTERN. A-PPucATlnN men APRJS, 19u.

Patented Mr.

3 SHEETS-SHEET 3.

INVENTOR .Zwfa m. man

76 i6/614.@ f MNM/f awk lanterns. `have in mind is to produce a light for the srarnsratrnrir entre LWELL NICOLS, OE SEW'ICKLEY, PENNSYLVANIA, ASSIGNOR TO H. C. FRY GLASS COMPANY, OF ROCHESTER, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

LANTERN.

Specification of Letters Patent, l 4

Patented Mar. 25, i919.

Application filed April 5, 1917. Serial No. 159,927.

ofthe United States, have invented or discovered certain new and4 useful Improvements in Lanterns, of which improvements the following is a speeieation. j

M y invention relates to improvements in The immediate object which I projection of motion pictures which shall be at once brilliant, steady, and economical to employ; but it will be understood, on

" reading the ensuing specification, that my improved lantern is widely applicable, Where bright and concentrated light is desu-ed: in spotelights for theaters, for example, in

lighthouses. and in many other specific uses;

Electric light is of all kinds of illumination the simplestand most satisfactory for the user to handle; and of electric lamps the two forms availablefor concentration are the arc lamp 'and the incandescent lamp.

lntil quite recently, the incandescent lamp has been so far inferior to the arc in inten sity that it has scarcely been considered for such service as motionf'picture projectors and spot-lights in theaters. Of late years, however, with the invention of filaments of new materials and the discovery of the good eii'ects of maintaining the filament in an atmosphere of inert gas such as nitrogen, rather than in vacuum, the candle-power practically attainable in incandescent lamps has been vastly increased. The arc lamp has still one notable superiority over .the incandeScent, when it comes .to projecting beams of intense light: the light emanatesl from a source of4 small dimensionsf-practically Vfrom :repeint-*and may accordingly be 4matter of diiiiculty; the light cannot be foeasily.

' cused and projected in sharply defined and properly confined pencils-at least, not

On the other hand, there are serioils objections and diiiiculties attending the use or' the nrc lamp for purposes such as I have indicated. The nature oi some oiI these objcctious'and diiiiculiics may be indicated: ln a spot-light, for instance. it is desirable that substantially all the light emanated from the source be gathered and vprojected in a narrow pencil. To accomplish this a mirror must be provided, and this mirror must be placed near the source of light. But the arc gives od vapors, and these, condensing and solidifying on the mirror surA 'face, corrode and dim it and diminish its effectiveness. The consequence is that a mirror with an'arc light (if provided at alll is of relatively little value. and, economically considered, the lamp is very wasteful of light'. Again, the arc light requires relatively great current strength, and is, on this account too, uneconomical. For mction-pic ture work the arc may not be produced by an alternating, but only by a direct, current; and at best it is noisy; the light iiickers; and there is need for an attendant constantly.V For another thing, the fire risk at tendant on the use of an open arc is high.

By my invention` l make the incandescent lamp available, avoiding the difficulties just mentioned, incident to the' use of the arc lamp. ln my use of the incandescent lamp, instead or" buildingit oflargc size (with the attendant diiiiculty already noted), l multiply the number of small-sized lamps, until l gain the candle-power desired, and l provide means for bringing together into one common pencil the light emanating from all of them. Since the actual dimensions ofthe light-source of each small-siZed'l'amp are small, and. Within limits practically permissible. l may focus and direct the pencils as I will, and unite them in a single shaft of light, which also is. Wholly within control for practical purposes.' 1 l In the accompanying.drawings, Figure 1 shows in longitudinal section the essential parts of the lantern of my invention; Fig. 2 is an end elevation of the organization shown in Fig. l; Fig. 3 shows in side elevation and in plan the light-deiecting member of Figs. l and 2; Fig. 4 is a view in longitudinal section of the essential arts of an other lantern, embodying'the Iundamental invention which is present also in the lantern ci Fig. l, and embodying also refinements upon that fundamental invention. Figs. 5 and 6 are views in longitudinal section andy in end elevation ot the essential parts of still another lantern embodying my invention; and Fig. 7

or' still another lantern. Fig. 8 shows in longitudinal sect-ion the essential parts of a lantern in which the light--dcflecting meniber is modified in form; Fig. 9 is a like View of another lantern in which the peculiar ends attained in` the lantern of Fig. 8 (as compared with those of Figs. l, d, and 7) are attained in another way. F lO-l'B show diagrammatically the theory of my invention. as it is embodied in the lanterns of Figs. l, si., and 7.

The essential element of thc, lantern of my invention is a member capable of changing the direction of a pencil of light Without changing the degree of concentration of the light, ot' which the pencil is composed. This essential element is constructed to so deal with a plurality ot beams of light, directed upon it from ditl'erent sources, and to turn into a common path or to 'ard a common focus, or in a common direction. the light received in such a plurality of beams. My lantern includes, associated with such an essential element. a plurality ot light sources. This essential element of iny intention may be a refractor, or it may be a reflector'. i

Referring firstto Figs. l, 2, and 3. thc reti-actor l is formed ot' glass or of other lightaefractiug material; it is, as will presently appear. essentially a prism member; and it. is in this instance in shape a hexagonal pyramid. About it is arranged a plurality ot' light soin-ces. In this instance these lighty sources are shown to consist of incandescent lamps ample) provided with parabolic reflectors. so that cach light source projects a pencil ot' lighty made up of substantially parallel rays. These. light. sources correspond in number to the faces ot the pyraniidal re-` tractor; and, .it being in this case a besagonal pyramid. there are six light sources. as indicated iii Fig. 2. The light sources are grouped symmetrically around the retractf'or, in a plane perpendicular to the prolonged axis of the pyramid. cach directly opposite one of the sixv sides of the pyramid (cf. Fig'. 2), and they project their pencils of light angularly upon the base of ther jiyramid (of.) Fig. l). T he pyramid is i1ideed a compound prism. including' as many there are sides to the prism elements as pyramid, The glass body bounded by and between the base of the pyramid and each one of its sides becomes a simple prism forl the light which cornes from that particular light source. which is ai' 'anged opposite the side under consideration; `the basal angle oi the pyramid is the retraeting angle of the prism. The liciiagoiial prism mightv indeed be cut. into SiX parte., and might consist lit.-

is a View in longitudinal section (nitrogen lamps, tor e.\:-v

Lacanau.

erally (as in effect) of six prisms. But, b

combining the six `prisms in, one pyramid there is manifest gain, for the glass in the central portionof the pyramidJ is in its cffcct part. not of one only, but of all six prisms. The arrangement is such that the light projected from the several sources in converging* paths upon the base othe py-y ramidal refractor l, passing through the refractory' is turned in direction, and emerges as a compound pencil. Iii such compound pencil, as will readily be understood, the components may overlap or be separate; preferably, they will come. into immediate contact but Will not greatly overlap; they may be directed to a common focus, orl in a common direction. As indicated in F ig.`1

they are turned into parallel contiguous within permissible practical limits, Whereas a single lamp of sulicient Size to give the total illumination which my lantern affords would of necessity have a lighbgiving elementv of dimensions too great to be practical for my intended purposes. The tot-al volume of light which my lantern projects is of course not six times the volume emanating from each source; some light is necessarily lost; but. the total so obtainableis greater than can be obtained from any sin glo source or" this nature. in condition to be directed and employed for such ends as I have indicated.

.eral light-givii-ig elements may-be small,`

In consequence of theel-rangement of the several light. sources in a group around the retractor, space is afforded for a number of' lamps; their number may be increased in definitely. I have said they are arranged in a common plane; andfso they are,'as they are shown in Figs. l andi?. Buttheir arrangement in a common plane is a correlative o their being :placed at equal distances from the i'et'raetor. The essential coiulition is that they shallgrouped around the rei'ifactoi', directingtheir pencils from the proper quarter' and at the proper angle upon the base of the refractor.

i have said above that, inthe lautern as il, is shown in Fig'. 1. the light'cinergcs trom the retractor 1 in a compoundl pencil ot'pnr alici rays. llt it be dtisiredfto change condition in this regard of the emitted lie a lens may be interposedl in its path. To such end l show in Fig, l part of the lantern a condensing lens 3. The eectof such a lens will be to direct the light to a focus. Figs. 8 andll show alternative means ot attaining thissame end; in Fig. 8 the base of the retractor lavis made lenticular, and the light isV brought, in the manner diagrammatically indicated, to a Jfocus f; in Fig 9 the refractor l is nnchanged,lbut the light source 2 includes a mirror which is ellip -soidal rather than parabolic; it emits a con-- vergent pencil, and this is brought by the refractor 1 to a focus at f. i

Chromatic aberration is a matter which must be taken into account. By selecting glass of proper quality this aberration may be so far diminished in amount as to be negligible; or, if'conditions of service make such a course desirable, the refractor may be built up in well known manner of pieces'of glassof dierent refractive power, and so rendered achromatic. y

As shown iii-Fig. 4, the number of refracting elements may be multiplied'. The refracting elements are placed in axial alinement. The second refracto'r, l, of Fig. a is, it will be seen, effective at vits' periphery'to retract the light cast uponv it from the light sources grouped immediately about it, while the light emitted through refractor l passes freely land without refraction through the plane central portion of retractor le. Refractor le is pyramidal, but is in shape the frustum of .a pyramid. Indeed the central portion of this reractor 1f might be cut awa '-and with advantage, for of necessity it will absorb some of the light passing through. But the cost of manufacture will be less if it be made as shown. However, the prism portion might be built up in the form of a ring or a polygonal continuous band, leaving the centralspace free for the passage of light. Such a multiplication of reractors manifestly provides for indefinite increase in the number of light sources.

As shown in Figs. 5 and the prism elements 1f are arranged with their refracting angles directed inwardly toward the axis of the lantern as a whole, instead of in opposite arrangement; and two things; it will be observed, are consequent upon this: first, the prism elements lbecome conveniently separate parts, and second, the paths of the pencils of light do not cross.

Fig. 7 shows a carrying forward of the multiple-unit idea of Fig. 4, so that an indeinite number of units Vmay be combined in tandem arrangement, while the whole is kept withinreasonable and practicable dimensions. Here is' involved, inv addition to what is shown in Fig. l, means for concentrating the compound pencil, as it passes from each unit in turn, and for causing the concentrated pencil to travel in parallel rays through the central part of the nest succeeding unit. The first unit l (beginning at the lett) is the unit of Fig. l, and requires no further description. The light which it projects will be understood to be a pencil of parallel rays. The succeeding refracting elements may be such elements as le of Fig. 4; so that, beyond the element l, the twice compounded beam of light advances in parallel rays. But the beam is larger, of greater cross-sectional area, than the beam advancing from the first unit. ln the path of this beam, beyond the element le, is arranged a condensing lens 3. rlihis lens 3, receiving the beam of parallel rays, causes the rays to con- Verge.- And then in turn, beyond lens 3, is arranged the lens 4 which, receiving the convergent pencil of light from lens 3, turns the rays divergently again, and causes the light t0 advance in a beam of parallel rays. But the beam is now of diminished size (though of increased concentration). It

follows that the next ensuing unit need not be of the large size otherwise necessary. Ordinarily the arrangement and power of the parts thus far described will be such that the successive refracting units (excepting the first, if desired) will be duplicates. Fig.

'Il shows also that, instead ot the reti-actingV unit 1b Vcombined. with the condensing lens 3,1 each of these succeeding umts may be 'such as shown at lg having a lenticular base. y

'The condensing lens 3 may thus be rendered unnecessary, and may be omitted. l believe this building up of units/.in tandem and iny indeinite number to be particularly applicable in such use lanterns in lighthouses.

The theory underlying my invention, so ar as concerns a refractor for-changing the direction of the light, will be well understood on considering the diagrams, Figs. 10, 11 and 12. Consider first Fig. 10. Suppose a pencil of light composed or' parallel rays to be travelino in the direction A. B, from A. to B, and ther-line A B to be the axis of the pencil; and su pose the object in view be to vturn the penci and to cause it to travel in the direction and on the axis BC. The medium is air and the refracting bod which is to elect the turning is glass. his refracting body then will be a prism; and

ioo

since, given such conditions as have been stated, refraction both of the entering and of the emerging ray will be toward the base olf' the prism, the arrangement will be that indicated in Fig. 1G, the prism F G H being so disposed that the base G H lies on the side of the broken line A B C toward which refraction is to occur, and the summit F on the opposite side. The degree of the retracting angle G F H determines, of course, the degree of refraction. For'simplicity of illustration the prism F Gr is shown to be an isosceles triangle, symmetrically placed, precisely on the line D E which bisects the :ingle AB C, Let itz-then be supposed that e. H ray tzuf'eling in the direetionfAf-B falls full upon the faceF G of theprism. lt Will. be rei'raeterl and be emitted from the fece F H as a my' aclnrzmoing.inthedireoiiiony B-`C. This is indeateclin dotted lines in Fig. l0; the pencil M',F,M'Q-Gr.makes-in-V cidence on tliefuoe" F G; and if;` is emitted fronNy the face F Hin tlieupeneilFMN.` H4". W. The problem .ie to combine the peueily e11iittedfom two light sources :rnd to 'cause them toi alvanee "together` in parallel l" rays, either side byffsifler or* overlapping (solo speak) nod-merged tli one 'into the other;

Fig. ll shows tivo light :sour-ees, A. endrl.`

and two light petlig wlthexesA. B andAf B". The Vtwo ideal'prsme l? G1 H of Fig. 131 may beoverlappeld (asitlivere) asindetecl in l*1 ig. 1l zuid combined fin u single refraeb* ing member F ll"V H(whieli "isth'e remeziiig member l of Fig. lyortheynmy be Sepev f rate prisms, or separiepafrts of aprisrir` body, iis'indiofited in Fig. 12; 'lf they bem-A' ranoferl Summit tor summif the" eklig of l ht arranged base to'bas'e, the `petlie of light will Cross, andjtbis is'thestate`othe ese in Figs. 1 il, and 7 ItoWxll 'be observed that moii` direction, ther eeveral` groups.; being:

in all eases the Several rpeiioils. initially directed to oonverge'are turned, sothelf the degree of eorivergencelis diminished, and, `1n Y the parteularins'iance, choseny for 'illustra-` tion', is actually reduced` tofzero-tlie refreet;- ed rays advancing in parallel lines.

'I elaiiii is my iI1V(-3iition`:`n`A

l. rIn a lantern.theeombnatioii of e, plurality of light sourees, a.p yremidal` pris; having a base and :L plurality of faces corlight from earl C `one side of the sources; upourliebase being 'een Lemme i responding in' s mi sources,y and i "i .lili

angle of refrzietioiro all elle `peiiei i "elle :prismubeing Subetantielly perpen-fouler.;i

to the besehereo. M l Y 2. la lantern, tlieyeombinetion of e, sue"- i cession of light refrroore, :and o 5]; light sources for eaclirefrretorr e soul-cee for .eeelr refraction being arranged erouxiclvi; mol projecting light oomergeiily. upon it, and the; whole arranged lio, giojee ine eoiirmon` direction llefllighiemd. uiting fromtheseverzilzsoureee. i 3. in e lanternthe-combination o' afpl n rality `ofl groups of `light-giving' unite, the unit-s ofeeelrgroup beiiigerrange to prow. ject pencils of light in Comferg light-Meeting element. ror oooh element *being erraigecl @thwart x of light eliminating; 1 :from :said: :ligli' A l 5 j units of "ille group mill adoptedWithout: will not cross (of. F1g."5); bue 1r they be` roule-end to ermee 'rlielight 'received from all the aseoeietedfunirs to adi'arree `1 1 escrime;

alned, and e lig leende-using `elemeril,ar-fl70 

